Yes i must addmit the phone never stopped ringing 12 months ago , and on the money side of things as long has these turbo's last 24 hours and have to be thrown in the bin afterwards w.g.a.f .

And because of the size of the engine used but being limited to only 650hp i wouldn't think two stonking great turbo's wouldn't have been implemented , so a couple of little vnt's would fit the bill nicely retrospectively speaking of course.

650 HP is the limit primarily because of the air restrictor and because of the boost limit to 2.94 bar absolute that is stipulated in the rules. If Audi could make more out of this engine within the framework of the rules I'm sure they would. Given a certain flow area, pressure and temperature, the mass of air that can inducted into the engine is fixed. This sets an upper limit of the amount of power an engine can produce, regardless of whether it's a gasser or Diesel.

But you're right inasmuch as they would only use as big a turbo as needed for the most optimum matching to the prevaling operating conditions in the race, but it still doesn't not explain why a VNT turbo is chosen instead of WG.

Anyway, nothing is substantiated so I won't go any further with this.

However, going back to the topic of thread, if we want to speculate a little about the compression ratio on the R10, I would put it between 15.0 - 16.5:1. Cold start is hardly an issue for a race car, and the key factor here would be choosing a CR for optimum thermal efficiency and minumum PCP. Best efficiency actually occurs around a CR of 14-16:1, so it is a safe assumption that the R10 would be somewhere in this area.

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Would i be right in thinking that the power produced here of 650hp could be easily doubled out of this engine or somewhere close , so in fact we'll probably look back in time and say it was well in a de-tuned state , and given/looking at the new bmw motor that's going to be put in the 272hp X5 at around 16.1 i would think the R10 would be 15.1 or lower as you've implied.

I don't think we can say in the future with the benefit of hindsight that this engine was "de-tuned" at 650 HP, just like we can't say that the first generation TDIs were de-tuned with only 90 HP when current ones are pushing nearly double that value from the factory with only 0.1L more displacement. Technology has and will continue advance and people will find ways to wring more output out of the engines over time; that much is a safe bet.

That being said, it's the technology of the time that limits what is possible. Based on current technology, I would bet the farm that we will not see future R10s making double of today's HP numbers. For one, I said before restrictors and boost limits will set an upper limit for horsepower that cannot be breached due to the laws of physics and thermodynamics.

And in fact, if it turns out that the R10 dominates Le Mans, you can be sure that next year Diesel entrants in general or Audi specifically will be slapped with further penalties to level the playing field, such as a weight penalty or more likely even smaller air restrictors or reduced boost limits.

We will see incremental improvements as technology advances; that's exactly what Audi wants to accomplish by putting Diesel power into Le Mans. Doubling the horsepower as you propose implies several possibilities: 1) Doubling the BMEP (analogous to engine torque) and hence cylinder pressure for a fixed given RPM limit; 2) Doubling the RPM at the same BMEP as current; or 3) some compromised combination of both.

At least from the best forecast of technology within the next 5 years, I can guarantee you that we will not see 1) or 2) in the R10. Firstly, doubling PCP in an aluminium crankcase will not happen even with the best design methodologies we currently know of without an unacceptable penalty in weight and bulk. Also, the gearbox has to be considered, and significantly increasing the torque also means beefing up the transmission, which adds weight. Second, to speak nothing about combustion rate limits, a doubling of RPM in a present-state DI-Diesel is challenging because of the minuscule amount of time available for fuel injection, mixing and burning. Further, forces in reciprocating components increase exponentially with increasing RPM. Doubling mean piston speeds roughly quadruples G-forces in the reciprocating parts, compounded by necessarily heavier components for a Diesel. Assuming the engine can run unrestricted, I think 150 HP/L will be a highly challenging barrier to break while maintaining competitive weight and reliability. This implies 825 HP for the current architecture and 5.5L displacement.

Now I know the Cummins boys are going to chime in and say that the 5.9s are pushing over 1000 HP, but I'm going to preempt their argument and just ask them to compare everything that I have just talked about: weight, torque limit, RPM, reliability (over a 24-hour race with over 80% at full-throttle, not just a 1/4 mile at a time or 95% part-load operation on the street), smoke-free emissions, engine architecture, etc...

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UUmmm yes miester you've just about covered every conceivable angel here for not being able to increase the power output of this engine , but it could go the other way in that the rules may be relaxed for everyone but the diesel entries.

I was talking with a nice guy today who rally's in the group N class with the evo 8's 9's and he said that there restricted to a 34mm pipe b4/at the turbo which limited power he said to around 320hp , but now there back up to around the 400hp some of which is by the way ( i've forgotten the term ) milling groves on the inside of the pipe work to increase velocity and flow , something they've been doing for some time i know but i may have it done.

I've seen the clip and read the article but didn't see any in depth pictures of the engine internals including the pistons... Do you have them that we could all see as well?

Download the Audi R10 clip and pause at 48 sec. mark. You can see the piston fairly well, but who's to say that is the actual piston? If I were Audi I'd probably show a 1.6 IDI piston being ringed. The general public wouldn't know the difference & they wouldn't be revealing their hand.

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yeap yeap... close to 30psi... hoping to get a Holset next winter...unless someone has one they'd like to donate this year. Otherwise, I'll be running a wastegated T3 base from a 300D that'll easily do 25-30psi all day long....
I'd really like to do the holset though in the NEAR future
Engine is currently "complete" to the bottom end. Working on the head now and waiting for tax $$$ to come in and a few parts to sell so I can get some of what is needed in the remainder... here is a pic "currently"

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